The present invention relates generally to improved packages and particularly to improved packages for containing blood and/or intravenous solutions such as saline, dextrose or glucose and which are made of sufficient amounts of materials which lend desirable film thickness as well as strength which is unaffected when the package is subjected to autoclaving and drop tests.
Various packages and bags have been developed over the years for retaining items which are to be sterilized by steam autoclaving after packaging. These bags typically comprise a plastic sheet material and a membrane permeable to sterilizing vapors such as ethylene oxide or steam. For example, U.S. Pat. Nos. 3,472,369 and 3,761,013 disclose bags consisting generally of a plastic sheet folded along longitudinal fold lines to define a longitudinal opening. The opening is covered by a readily removable, vapor-permeable closure membrane typically in the form of a paper strip. It has been found that when such bags are made large enough to hold bulky, relatively heavy materials, such as blood or saline solution, the stress that is developed when the bag is filled may result in rupturing of the seals joining the plastic sheet material and paper membrane. This problem is particularly aggravated when the filled bag is subjected to steam sterilization--autoclaving--which, by itself, effectuates a weakening of the membrane.
Heretofore, blood and intravenous solution containers were made from glass and were then superceded by containers made from polyvinyl chloride (hereinafter referred to as "PVC"). There is a great deal of dissatisfaction with PVC containers because large amounts of plasticizers and vinylchloride monomers leach and/or hydrolyze into the blood and/or intravenous solutions contained in PVC bags and ultimately find their way into humans and animals being treated. The containers made of a polyvinyl chloride formulation include as an ester-type plasticizer, di-2-ethylhexylphthalate. This system of storage of blood and blood components results in a surprisingly low plasma hemogloben content after, for example, 21 days of storage however, each year more and more concern surfaces from various sources with regard to the potential undesirability of the plasticizer leaching from the plastic material and entering the blood stream, from where it is infused to the patient upon infusion of the blood or blood components. This concern also includes possible long-term and subtle effects of the PVC. Even now, Canada has prohibited the use of the PVC package for containing intravenous solutions because of the long term harmful effects attributable to PVC.
Various plastic formulations which are flexible, sterilizable at autoclavable temperatures, free from liquid plasticizers capable of leaching, as well as those which exhibit high strength and impact resistance have been tested as blood bag materials. Polypropylene, used alone is too brittle and is known to break on impact from drop tests.
A material for use in making blood and/or intravenous solution packages should have the following properties:
(1) The package should be readily processable--the material should process readily into film or sheet by conventional extrusion techniques. Preferably, the film should be of less thickness than that of the present plasticized PVC film (0.015 inches). The film should not be subject to blocking, in film form, to any extent which would interfere with container fabrication. The material should show no significant tendency, in film form, to develop or maintain electrostatic charges during fabrication, filling, storage or use of the container. In addition, the material should mold readily into fittings or other parts by ordinary injection molding. Port components should be of the same material as the bag to satisfy requirements due to the contact between the material and the solution or blood. Material should also be readily heat sealable by conventional or impulse heat methods or by dielectric (RF) methods.
(2) The material should possess high contact clarity versus packaged solutions.
(3) The material should have a minimal effect (less than 0.5 unit) upon the pH of non-buffered fluids, such as pure water, during manufacture and through the shelf life of the product.
(4) The material should show minimal visually noticeable color after fabrication, filling and sterilization of the container.
(5) The materials should show no cracking upon flexing due to storage, shipment and handling at temperatures 5.degree. C. to 40.degree. C. (41.degree. F. to 104.degree. F.).
(6) The material should show no tendency toward environmental stress or rupture under conditions of fabrication, storage and use.
(7) The material should readily accept printing, by either a stamp or flexigraphic process.
(8) The material should be stable toward ordinary light, natural and artificial, at levels encountered during usual product storage conditions. The material should also exhibit long-term stability with general physical, chemical and biological properties essentially unchanged, of no less than (4) years under warehouse storage conditions, as supplied or in molded part or extruded sheet form, not in contact with solutions and must be stable for warehousing. In addition, the material should possess acceptable stability toward ionizing radiation of up to 2.5 Mrad.